Signaling system



J. O. CARR SIGNALING SYSTEM Oct. 13, 1936.

Filed Feb. 21, 1928 I I I I I l I I l J (019 III P Patented Oct. 13,1936 PATENT OFFICE SIGNALING SYSTEM John O. Carr, Chicago, Ill.,assignor to Teletype Corporation, Chicago, Ill., a corporation ofDelaware Application February 21, 1928, Serial No. 255,918

9 Claims.

My invention relates to signaling systems and more particularly myinvention relates to intercommunicating systems especially adapted foroperation between outlying stations in which the telegraph or othersignaling apparatus located thereat is normally maintained in anon-operating condition and is arranged to be started into operationfrom a central station.

With the expansion of telegraph systems, automatic apparatus is beingmade part of the equipment in outlying stations where the normal amountof trafiic is not sufficient to keep the system in continuous operation.A need has therefore risen for the development of circuit arrangementswhereby the apparatus in these outlying stations can be normallymaintained in a nonoperating condition and automatically started intooperation from a central station to permit intercommunication betweenthese outlying stag" tions.

An object of my invention is to provide means for normally maintainingthe automatic signaling apparatus at all of various outlying stationsnormally in non-operating condition and remotely disposed switchingmechanism arranged to selectively start the apparatus into operation forintercommunication between the outlying stations.

Another object of my inveition is to provide 39 simple circuitarrangements whereby an operator at a central station can with the useof the regular telegraph line start into operation and interconnect thetelegraph apparatus at two outlying stations. Still another object of myinvention is to provide means for varying the constants of a telegraphcircuit to permit communication between any of a number of remotelydisposed stations at unequal distances apart.

Other objects of the invention together with the foregoing will appearin the specification which follows and are such as may be attained by autilization of the various combinations, subcombinations and principleshereinafter set forth Referring to the drawing:

The figure shows in diagram the apparatus and circuit arrangementsemployed in carrying out the form of my invention.

Referring nowmore particularlyto the drawing, a plurality of outlyingstations A to F are shown with circuit connections to a central stationG. Located at each of the outlying stations is a telegraph typewriterunit comprising preferably a 55 transmitting contact I, of a singlecontact transand defined by the terms of the appended claims.

mitter and a selector magnet 2 connected in series with the transmittercontact and controlling a printer such for example as is disclosed inthe patent to Kleinschmidt 1,567,392 issued December 29, 1925. Althougha single magnet printer and single contact transmitter is illustratedfor purposes of convenience, it will be evident from the descriptionwhich follows that any other form of telegraph apparatus may beemployed. The transmitting contact I is normally closed and ispreferably shunted by a condenser 3. The transmitter and receiver aredriven by a normally nonoperating motor 4 supplied by energy from thesource of the circuit for electrical energy 5 and the circuit of whichis controlled by the armature of biased polar relay 6. Relay 6 is biasedto hold the circuit for motor 4 closed. With a current of positivepolarity impressed on the polar relay 6, the bias is overcome and itsarmature is held in position to break the motor circuit. When current ofopposite polarity or negative current is impressed on polar relay 6, thearmature of relay 6 is moved to its biased position, closing the motorcircuit. Thereafter the armature remains in this position until thepolarity of the current through winding of relay 6 is again reversed tomove the armature from its biased position to open'the motor circuit.The polarity of the current normally impressed on the relay 6 is suchthat it holds the circuit of the printer motor 4 open as shown. Theprinter is thus normally maintained in a non-operating condition.

The main winding of polar relay 6, the transmitter contact i and theprinter operating relay 2, are connected in series with the signalingline 1 through hand signaling key 1'. Line 1 connects the outlyingstation A with the central operating station G.

Located at the central operating station there is a switching unit andsignal device individual to each outlying station comprising ananswering jack 8, called jack 9, calling jack l0, and neutral relay I iconnected in the signaling line 1. Relay ll controls an energizingcircuit for signal lamp ll The calling jack 10 comprises a spring I2operating between two contacts l3 and I4, and spring l5 normally inengagement with its lower contact is. The contact I6 is connectedthrough resistance IT to ground at I8 and controls the ground returncircuit which may be completed through resistance I! or directly toground in a manner to be described hereinafter. The spring I5 isconnected to the signaling line 7 extending to the outlying station andis also connected over side of battery 34 thru this contact.

Called jack 9 comprises a spring 20 normally disengaged from contact 26and spring 21 normally in engagement with contact 28. Contact 26 isconnected to ground at I8 over conductor 29 and prepares an electricalpath which shunts resistance |1. Spring 21 is connected to the signalingline 1.

The answering jack 8 comprises springs 23, 25 and 3|.

The other side of the battery-is grounded at 35. Negative potential frombattery 34 is impressed on the signaling line overconductor 24 andspring |2 of the calling jack ID as will be described in more detailhereinafters 1 Spring 23in engagement with contact 36 is connectedto thespring 21 over the conductor 31 for controlling the circuit from thepositive side of battery 2| to signaling line 1.

An answering set comprises printer operating relay 40 for operating asingle magnet printer and transmitter contact 4| of a single contact,

transmitter is located at the central station for signaling with any oneor more of the outlying stations and is connected in series with plug 42over the conductor 43. The plug 42 when inserted in answering jack 8,will move spring 25 to disengage its contact 33, spring 23, to disengagecontact 36 and spring 3| to engage contact 44. Connecting cords such asfor completing circuits from the calling jack individual to one stationwith the called jack of another station is also part of the centralstation equipment.

Although a plurality of batteries have been shown for purposes ofconvenience in illustrating the invention, it will be understood that inpractice, a single battery may be employed.

Having described theapparatus and the circuit arrangements in general, adetailed description of the operations, which take place in connectingany two outlying stations for inter-communication will now be given.

With the apparatus in its'normal non-operating condition, there are noplugs inserted in the jacks and connections are made as shown in thedrawing. Current of positive polarity is impressed upon the signalingline 1, extending to outlying station A from ground through the battery2| at the central station, the contact I3 in engagement with spring I2,conductor 22, spring 23, in engagement with its contact 36, conductor31, the contact 28 in engagement with spring 21., relay over thesignaling line 1 to the outlying station A through the winding of theoperating magnet 2, transmitter contact polar relay 6, and over thesignaling line 1 and to spring IS in engagement with its contact l6 andresistance l1 to ground. A similar circuit impressing positive currenton the signaling line is completed through all the other jacks and theirassociated outlying stations.

With the system in this condition, the bias winding of the polar relay 6maintains its armature in the position shown and the circuit for theSpring 25 is normally in engagement with contact 33 and is connected tothe negative motor operating the telegraph apparatus is open at thisarmature. The telegraph apparatus is therefore normally in non-operatingcondition. Assuming the operator at the outlying station A, desires tocommunicate with outlying station B, he will call the central station bymomentarily opening signal key 1. Relay II will be de-energized duringthe momentary opening of the line to close 'a circuit for the lamp II.This will be repeated until the operators attention is attracted. Theoperator at the central station when thus attracted will insert plug 42in the answering jack 8, disengaging the springs 25 and 23 from theircontacts and closing the contact 44 and spring 3|. The disengagementof'the con: tact 36 from spring 23 disconnects the positive battery fromthe signaling line 1 the circuit for which as will be recalled from thedescription above, was completed through this contact.

The circuit for battery 34, which is completed through spring 25 and theconductor 24 to the calling jack at contact M is opened at contact 33.

spring 3| and plug 42 over conductor 43 to the tact transmitter 4| inseries to the connector 46,

conductor 31, contact 28, spring 21, relay signaling line 1, to thewinding of the printer operating relay 2 transmitter contact I, polarrelay However, a circuit is completed from ground through battery 34,contact 44 in engagement with- 6, to the spring l5, contact I6 andthrough resistthrough the contact 44 at the answering jack, the

telegraph apparatus at the central station, over the spring 21 of thecalled jack 9, and thence to the signaling line 1.

When the negative potential is thus connected 7 to the signaling line 1,polar relay 6 operates its armature, closingthe energizing circuit forthe motor 4. Motor 4 starts the printing set at the outlying station Ainto operation.

With the motor at the Outlying. station. now in operation, telegraphsignaling can now take place between the outlying station A and thecentral station G, the signalingycircuit traced above, being completedthru the contact of'the transmitter and the receiving relay '2 at theoutlying station and thru the transmitter contact 4| and the receivingrelay 40 at the central station. Synchronism between these telegraphsets will be maintained inthe manner well' known in the art and is notshown as itdoes not form part of this invention.

If now the operator at the outlying station A desires to get intocommunication with the opcrater at the outlying station E, he transmitsthis information to the operator at the central station G. Upon receiptof this information, the operator at the central station will insertplug 41 into the calling jack I0 associated with the calling outlyingstation A, and insert plug 48 into the called jack 9 of the outlyingstation B.

Inserting the plug 41 into the calling jack I0 disengages the spring l5from its contact l6,

removing the ground connection at this point and simultaneouslyextending this circuit thru the connection cord 45. At the same timespring I 2 ismoved to disengage contact l3 and engage contact I 4,opening a further point in the circuit of battery 2| and preparing acircuit for the battery 34 from spring 25 of answering jack 8. Thiscircuit is however, at this time still open at spring 25.

Plug 48 at the opposite end of the connecting cord when inserted in thecalled jack 9 associated with outlying station B, disconnects spring 27from its contact 28 and connects spring 2!! with contact 26.Disengagement of spring 2! from contact 28 opens the circuit of battery2| completed over signaling line 1 to outlying station B, therebyremoving the positive potential from this line. The engagement of spring29 and contact 26 connects the signaling line 1 directly to ground at l8by passing resistance H, the circuit to ground having formerly beencompleted over spring l5, contact l6 and resistance IT as was describedin detail above.

A circuit is now completed from ground at the central station throughthe negative battery 34, the contact 44 of answering jack 8 associatedwith outlying station A, plug 42, conductor 43, receiving relay 46,transmitter contact 4i, connector 46, conductor 31, contact 28, spring2V, relay ll, signaling line i to the outlying station A, printeroperating relay 2, transmitter contact I, the winding of polar relay 6,the other side of the signaling line 1, spring i5 in engagement I withthe plug 41, connecting cord 45, plug 48 in engagement with the spring27, of the called jack 9 associated with the outlying station B relay llone side of the signaling line i extending to the outlying station E tothe winding of the printer operating relay 2, transmitter contact I, thewinding of the biased polar relay 8, the other side of the signalingline 1, spring as in engagement with its contact 26 to ground overconductor 29.

As a result of negative polarity being impressed upon line I to stationB, the armature of polar relay 6 at that station moves to engage itsfront contact to complete the circuit for the motor 4. As the motorcircuit is thus completed, it starts into operation and in turn startsthe telegraph apparatus at the outlying station B into operation.

The signaling circuit is now completed over the circuit which was tracedabove for permitting signaling between the outlying station A andoutlying station B, the circuit being completed through the printerrelays and transmitter contacts at each station in series. It will benoted also that in the above circuit the receiving relay and transmittercontact of the telegraph set at the central station is also connected inthe circuit.

If desired, however, the operator at the central station may disconnectthe answering set by removing the plug 42 from the answering jack 8. Thebattery 34 will then still be connected to the circuit traced aboveexcept that instead of being directly connected to the signaling line llover conductor 31, the circuit is now completed from ground through thebattery 34 over the contact 33 in engagement with spring 25 of theanswering jack 8, conductor 24, the contact 14 in engagement with springI2, conductor 22, spring 23 in engagement with contact 36, conductor 31,contact 28 in engagement with spring '31, relay H over signaling line ito the telegraph apparatus at outlying station A. The circuit from thispoint on including the apparatus at receiving station B is identicalwith that traced above.

The circuit, it will be noted, is now again completed from the receivingand transmitting apparatus at each of the outlying stations through thecalling jack individual to station A, and called jack individual tostation B. Signaling between outlying stations A and B can now beconducted in the usual manner.

As soon as the operators at the two outlying stations are throughcommunicating with each other, the operator at the central stationremoves the plug 41 from the calling jack l0 and called jack 9. As aresult the battery 34 is disconnected from the circuit traced above andthe circuits originally traced including battery 2| are completedthrough the individual jacks to each outlying station. A potential ofpositive polarity is impressed on the signaling line I by battery 25 andas a result the polar relays function to move their armatures todisengage to open the circuits of the motors 4. The telegraph apparatusis thus restored to its normal non-operating condition.

It will be noted that during the signaling operations above described,the relay H is energized and deenergized as the signaling line is openedand closed to transmit signals. As the relay ill is energized anddeenergized, the lamp i flashes. The operator is thus provided with anindication that the connected stations are communicating. At the end ofthe signaling, the dashing will stop and the operator will thereforebreak circuit inter-connection. Outlying stations C to D are eachseparately connected to the central station G as are stations A and B.

It will be evident from the above description that a very simplearrangement is provided for maintaining the apparatus at variousoutlying stations normally in non-operating condition while at the sametime by comparatively simple circuit arrangements including only theregular signaling line, the telegraph apparatus can be started intooperation from a central or connecting station to enableintercommunication between outlying stations or between one or moreoutlying stations and the central station. It is evident of course, fromthe above description that any number of outlying stations can beconnected in circuit with each other.

Although I have shown my invention as applying to a manual exchangestation, it is evident of course, that my invention has application alsoto an automatic or semi-automatic central station.

Having described preferred embodiments of my invention, what is desiredto be secured by Letters Patent and claimed as new is:-

1. In a signaling system, a central station, a plurality of outlyingstations, a plurality of lines connecting said outlying stationsindividually to said central station, automatic telegraph apparatus ateach of said outlying stations and at said central station, means forelectrically connecting said central station telegraph apparatus to anyone of said outlying stations, and means for electrically connectingsaid outlying stations to each other in a plurality of concurrentconnections for independent intercommunications, said means beingsimultaneously operative for changing the signal line characteristics tocompensate for the line resistance between said central oflice and saidoutlying stations.

2. In a signaling system, a plurality of outlying stations, a centralstation, a plurality of electrically independent signaling linesconnecting said central station with each of said outlying stationsindividually, telegraph apparatus at each of said outlying stations andat said central station, means including pairs of said signaling linesbetween said central station and pairs of said outlying stations forsignaling between pairs of said outlying stations in a plurality ofconcurrent connections for independent intercommunications, and meansfor modifying the characteristics of said circuits to compensate for theresistance in any of said connections between said outlying stations.

3. In a telegraph system, a plurality of stations and a central station,a plurality of station telegraph sets and a central station telegraphset, a central switchboard comprising jacks and resistances individualto each of said stations, switching contacts in said jacks, circuitconnections including said contacts of said jacks and said resistancesbetween each of said stations and said central switchboard, meansincluding the contacts of one of said jacks and one of said resistancesto form a communication connection including one of said stations andone of said resistances and said central station telegraph set, andfurther means for forming a plurality of concurrent intercommunicationconnections including said stations in pairs and excluding saidresistances.

4. In a telegraph system, a plurality of outlying stations, a centralstation, circuit connections between said central station and each ofsaid outlying stations, circuit resistances at said central station andone included in each of said circuit connections, signaling meansincluding one of said circuit connections for signaling between one ofsaid outlying stations and said central station and including in eachsuch signaling means the individual circuit resistance of the outlyingsignaling station, and means at said central station for connecting aplurality of said outlying stations to each other in pairs forconcurrent independent intercommunications and for simultaneouslyexcluding said circuit resistances to compensate for the increased lineresistance in each connection between outlying stations.

5. A printing telegraph exchange system comprising a central station, aplurality of subscriber stations, a plurality of telegraph subscriberlines interconnecting said central station and said subscriber stations,a plurality of resistances in series with said lines individually,central switching means to effect a communication circuit comprisingsaid central station, a subscriber station, a line and its individualresistance in series, manually operable link circuits at said centralstation for interconnecting said subscriber stations, means at each ofsaid stations for transmitting and receiving impulses, and means at saidcentral station effective upon interconnection of any two of saidsubscriber lines for compensating for the increase in resistance in thesignaling circuit including said transmitting and said receivingapparatus by excluding said resistances from the signaling circuit. 7

s 6. A printing telegraph exchange system. comprising a central station,a plurality of subscriber stations, a plurality of telegraph subscriberlines interconnecting said central station and said subscriber stations,link lines at said central station, means at each of said stations fortransmitting and receiving impulses over said subscriber lines, saidsubscriber lines being of a predetermined resistance, means at saidcentral station to connect one of said subscriber lines to said centralstation for communication While maintaining the full predeterminedresistance value of said connected line, and means effective uponinterconnection of any two of said subscriber lines by the link linesfor automatically reducing the resistance of each of said subscriberlines to compensate against increased resistance of said lines inseries.

7. In a printing telegraph exchange, a plurality of signaling circuitseach comprising a resistance,

a line conductor and a telegraph station set, a further telegraphstation set, switching means to connect said further set in series withone of said circuits While retaining said resistance in said circuit,and further means toconnect together two of said signaling circuits inseries and excluding said resistances of said connected circuits.

8. In a printing telegraph exchange, a plurality of signaling circuitseach comp-rising a resistance, a line conductor and a telegraph stationset, a further telegraph station set, switching means to connect saidfurther set in series with one of said circuits while retaining saidresistance in said circuit, and further means to connect together two ofsaid signaling circuits and said further set in series and excludingsaid resistances of said connected circuits.

9. In a printing telegraph exchange, a plurality of-signaling circuitseach comprising a resistance,

a plurality of jack contacts, a line conductor and:

a telegraph station set, a further telegraph station set, switchingmeans to connect said further through said jack contacts and excludingsaid resistances of said connected circuits by operation of further jackcontacts.

JOHN O. CARR'

